执行apt-get upgrade后Passenger启动失败，求排查方向

Hey there, let's walk through the key troubleshooting angles for your Passenger issue after running apt-get upgrade—since you've already confirmed rake is installed, your Ruby 2.4.0 setup is correct, and the webuser is configured properly, here are the areas to dig into:

• Validate Passenger & Nginx Version Compatibility
  An apt-get upgrade might have bumped Nginx to a version that clashes with your installed Passenger. First, check the current versions:

  passenger -v
  nginx -v
  

  Cross-reference these against Passenger's compatibility guidelines (you can pull up local docs with passenger-doc or recall the supported Nginx versions for your Passenger release). If there's a mismatch, you’ll need to either downgrade Nginx to a compatible version or update Passenger via RVM or the official Passenger repository.

• Double-Check Passenger's Ruby Path Configuration
  Even if your webuser has Ruby 2.4.0 set correctly, Passenger might be picking up a wrong Ruby path post-upgrade. Open your Nginx site config (typically in /etc/nginx/sites-available/your-app.conf) and look for this line:

  passenger_ruby /path/to/your/ruby2.4.0;
  

  Confirm the path points to your RVM-managed Ruby 2.4.0 (get the correct path by running which ruby while logged in as webuser). Also, make sure the webuser has read access to this Ruby directory.

• Inspect Passenger & Nginx Error Logs
  Don’t limit yourself to access.log—Passenger and Nginx’s error logs hold way more clues for startup failures. Check these files:

  • /var/log/passenger.log
  • /var/log/nginx/error.log
    Look for errors like missing gems, permission denied messages, or Ruby environment mismatches. For example, if it complains about rake, verify the gem is installed in your Ruby 2.4.0 gemset:

  rvm use 2.4.0
  gem list rake
  

• Verify File Permissions Post-Upgrade
  Sometimes apt-get upgrade resets permissions for Nginx/Passenger-related directories. Ensure:

  • Your webuser has read/write access to your Rails app’s root, tmp, and log folders.
  • The Passenger agent (usually running as www-data or your webuser) can access Ruby binaries and gem files.
    Run a quick permission check with:

  sudo ls -ld /path/to/your/app/
  sudo ls -ld ~webuser/.rvm/rubies/ruby-2.4.0/
  

• Recompile Passenger for the Updated Nginx
  If Nginx was updated, Passenger’s module might need recompiling to match the new version. Try:

  passenger-install-nginx-module
  

  Or if you’re using the packaged Passenger-Nginx, reinstall Passenger:

  sudo apt-get install --reinstall passenger
  

  Then restart Nginx to apply changes:

  sudo systemctl restart nginx
  

• Ensure RVM Environment Loads for the Web Server
  Nginx/Passenger might not be initializing the RVM environment correctly for your webuser. Add these lines to your Nginx server block to force the right environment variables:

  passenger_env_var PATH /home/webuser/.rvm/gems/ruby-2.4.0/bin:/home/webuser/.rvm/gems/ruby-2.4.0@global/bin:/home/webuser/.rvm/rubies/ruby-2.4.0/bin:$PATH;
  passenger_env_var GEM_HOME /home/webuser/.rvm/gems/ruby-2.4.0;
  passenger_env_var GEM_PATH /home/webuser/.rvm/gems/ruby-2.4.0:/home/webuser/.rvm/gems/ruby-2.4.0@global;
  

  Restart Nginx after updating the config and test again.

内容的提问来源于stack exchange，提问作者Confused Vorlon